Packaging containers of the single-use disposable type for beverages such as milk and juice are often manufactured from a flexible, laminated packaging material which consists of a central core, or carrier layer of fibrous material, e.g. paper, which is coated on either side with homogeneous layers of thermoplastic material, for example polyethylene. The packaging material may also include additional layers in order, for example, to improve the light or bacteria tightness properties of the material, e.g. aluminium foil (Alifoil). The thus formed packaging laminate is reformed using per se known packing and filling machines by folding and sealing into individual packaging containers filled with liquid contents. The packaging containers are provided with different types of opening arrangements which, in their simplest form, may consist of a printed opening indication, and which, in more sophisticated packaging containers, may consist of a prefabricated, e.g. thermoformed opening and re-closure arrangement which is placed over a prepared opening region in the packaging container.
In prior art packaging containers which are provided with separately manufactured opening arrangements, for example produced by injection moulding, these are placed over a prepared opening region in the wall of the packaging container. The opening region normally consists of a hole punched through the wall and covered with a separate, tear-off covering strip which is thermosealed to the container wall around the hole. The separately-manufactured opening and re-closure arrangement comprises a fixed part with a frame sealed around the hole and a moving part pivotally connected to the fixed part. The moving part is in the form of a lid which, by snap action, may be connected to the fixed part so that it will be possible to re-close the packaging container in liquid-tight fashion once it has been opened for the first time. An opening arrangement of this type is described in greater detail in, for example, European Patent Application 97919839.7, to which reference is made for further information.
From the consumer point of view, it may be seen as a disadvantage that, in the above-described prior art type of opening arrangement, the outer lid must first be opened and thereafter, in a separate operation, the tear-off strip located within the frame of the fixed part is to be torn off so that the contents of the packaging container will be accessible for pouring. A second, prior art type of opening arrangement (European Patent Specification 280.023) offers a solution according to which the packaging laminate is automatically penetrated on the opening of the opening and re-closure arrangement. This opening arrangement similarly includes a fixed part which is applied on the outside of a packaging container and includes an aperture which coincides with a prepared opening region in the wall of the packaging container. The prepared opening region comprises a thinner material layer, which, for example, has been realised in that one or more of the layers included in the original laminate has been removed in the opening region, or in that an aperture punched through the wall is covered with an additional layer of, for example, thin plastic. The opening arrangement further includes a moving part which is displaceably connected to the fixed part and capable of being moved between a forward position closing the packaging container and a rear position in which the packaging container is open. On displacement of the moving part from the forward to the rear position, the weakened portion of the packaging laminate is simultaneously torn off in that a projecting tearing device or plough penetrates through the packaging container wall and tears off the weakened portion thereof. It will thus hereby be possible for the consumer, employing but a single opening operation, to open the packaging container so that its contents may be poured out via the opening and re-closure arrangement. This may thereafter be re-closed in that the moving part is displaced from its rear to its forward position, i.e. the position which the moving part had assumed from the outset when the packaging container was still unopened. One drawback inherent in this type of opening arrangement is that the consumer has no visual, reliable indication as to whether the packaging container had previously been tampered with or opened. As the wish that the packaging container be simple to open in a single operation has been satisfied, the separate tear-off strip (which had previously been rendered visible and torn off manually when the packaging container was opened for the first time) is now dispensed with. No arrangement or method for making it visually apparent to the consumer that a re-closed packaging container of this type had previously been opened has hitherto been realised.
There is, thus, a general need within the packaging industry to realise an opening arrangement of the above-mentioned type which is simple to operate for the consumer and which requires no separate tearing off of a covering strip or the like, but which nevertheless affords a clear and reliable indication when the packaging container had previously been opened.